Cross platform string encryption

I am looking for a method of encrypting a string on an iPhone, passing that to a web server (asp.net c#) and decrypting it there for processing, and return a response.

I think that I know how to send the encrypted string and then return the result, 开发者_高级运维but I don't know what encryption will work on iPhone and asp.net.

Any suggestions? Sample code would be helpful, especially on the iPhone side, if at all possible.

read this:

http://iphonedevelopment.blogspot.com/2009/02/strong-encryption-for-cocoa-cocoa-touch.html

What's the best encryption algorithm for the iPhone in terms of speed and security?

AES Encryption for an NSString on the iPhone